This invention is concerned generally with sealing all kinds of liquid containers having a profiled rim portion (lip) and charged with a nonpressurized fluid or with a liquid that produces a limited internal pressure and that upon completion of the filling operation are not subject to any heat treatment. Furthermore, this invention is concerned with sealing containers that upon completion of the filling operation and upon their closure are reopened and closed again only once or a limited number of times.
Prior art fluid-tight closures made of plastic material have been described for example in the periodical Z-Konstruktion 28 (1976), copy 7, page 257, published by Springer Verlog, Federal Republic of Germany. The closures disclosed in this periodical are of the type suitable for closing bottles or tubes having interface sealing means and using for the multiplication of sealing force elbow levers, simple wedges or double wedges and threads. The closures of this type are complicated in structure and costly in manufacture and are designed for frequent alternation of their function, that means for repeated closing and opening of the container.
Another technical solution is described in the German Pat. No. 2,512,882 which discloses a shrinkable plastic foil bent over the rim of a container so that upon its heating the foil due to the shrinking effect hermetically seals the rim. The disadvantage of the shrinkable foil is the fact that wrinkles and folds resulting from bending the foil over the projecting rim portion, are not eliminated during the shrinking process so that this type of closure is applicable for bottles having short rim portions only. Considering closures of another material such as crown cork closures or aluminum disk caps conventional for closing bottle necks, they have the disadvantage that upon opening the bottle they cannot resume their sealing function.